As in historical on-readings ending in -ゐ, such as "つゐ", "ゆゐ", and "るゐ", most dictionaries do not have "すゐ" and "すゐ" as historical readings for 穗. According to historical data, the on-readings of 穗 are the modern "すい" and "ずい". However, the Dai Kanwa Jiten, has the -ゐ historical on-readings.